Tuning cammed LS1's with large injectors?

[ViolatorTA]

Ok. The frustration has started again already. I've managed to get most of my VE dialed in except the lower MAP regions. 15kpa row tunes out fine. 40kpa/up tunes fine from 1600rpm's/up. 400rpm-1200rpm/20kpa-35kpa always reads rich. Anywhere from .87-.94 no matter how many changes until it gets to where I stop figuring something has got to be lean. The map can go from 33.9 in the 15kpa/2000rpm cell to 21 in the 20kpa/2000rpm cell and still read rich. This process seems to follow suit throughout the regions mentioned above. Has anyone had this happen and if so what is the proper approach to tuning these areas right?

[pkincy]

You don't give any detail on your car, but if you still are mass air flow the changes to VE only offer a secondary check on the fueling.

Your primary check is the MAF frequency which tells the pcm what the air flow rate is and than the pulse width is ordered based on the IFR.

What have you entered (your "large injectors") in the IFR table. And how did you calculate the flow rates that you have entered?

Perry

[AGRO]

what size are your injectors?

[ViolatorTA]

Sorry. Forgot it's been so long since I've been in here.

The car is in AutoVE mode. No MAF. It's a 99 Trans Am, LS1, 231/237 TSP cam on a 112lsa. LS6 intake, ported throttle body and Racetronix 42.5lb injectors. The IFR table has been scaled using actual FP at idle(61lbs) and RHS's .xls spreadsheet. These are the numbers.

6.312500
6.343750
6.382813
6.421875
6.460938
6.492188
6.531250
6.570313
6.601563
6.640625
6.671875
6.710938
6.742188
6.781250
6.812500
6.851563
6.882813

[pkincy]

I have the same injectors and ended up as below:

Now I am not saying this is correct as it is a lower IFR at the wot (0 kPa Vacuum <100 kPa MAP> remember the table is backwards) and a higher IFR at low MAP high Vacuum) than indicated by the injector calculator xcel spreadsheet but it has worked for me. I am using a MAF. And have tweaked my VEs up in the 70 + MAP region as well as the high rpm regions and down in the idle and normal cruise regions.

Some of this IFR tweaking came from measuring my Fuel Pressure and realizing that while I am 58 psi at idle at wot I am between 52 and 55 depending on RPM, as the Excel spreadsheet assumes constant rail pressure I had to end up tweaking IFR to compensate.

LABELS Injector Flow Rate (Grams/Second)
Manifold Vacuum kPa {link: GM.MANVAC} Value
0 5.890625
5 5.976563
10 6.070313
15 6.148438
20 6.226563
25 6.304688
30 6.382813
35 6.460938
40 6.546875
45 6.640625
50 6.742188
55 6.843750
60 6.945313
65 7.046875
70 7.148438
75 7.257813
80 7.367188

Also take your time on logging. I get way more useful logs when I concentrate on getting each individual FTC correct. So log with the FTC in a prominent place next to your LTFTs and STFTs and see what is happening in each cell. Get that cell correct first working on VE and move on to the next.

One of these days I will get my WB calibrated and can Auto VE tune and it will become easier. I presume you, like I, are tuning using logged data not including a logged WB.

Perry

[98SS2836]

Are you going to throw juice at that. Thats a pretty big injector.

[pkincy]

That is a valid point. I only hit 60% duty cycle or so in my 402 with them.

They do tune easily however, so will work reasonably well in smaller motors.

Perry

[ViolatorTA]

Yes, I have a 150 shot I plan to spray but I really need to get this part of the tuning straight first before thinking about tuning for the nitrous.

I've been using an LC1 WB for logging setting up AutoVE and this problem is frustrating. I'll try playing with the IFR table but am at a sort of loss.